‘Did you ever see pictures of Pompeii?’ Whitestone said, more to herself than to me. ‘They look like they’re screaming, don’t they? They look like they’re going to be screaming for ever.’

‘He was going to come in,’ I said. ‘He was going to make a statement.’

Whitestone looked at me and shook her head. ‘Mr Khan agreed to be interviewed in the presence of his lawyer,’ she said. ‘That’s all.’

‘But how did he die?’

Whitestone gestured angrily at the screen. ‘How do you think he died? He died in the fire.’

Then I was through the door and into the mortuary, and Elsa Olsen was looking up from the burned cadaver on the stainless steel slab before her.

‘Scrubs and hairnets, Wolfe. You know that.’

‘How did he die, Elsa?’

Whitestone was right behind me.

‘How did he die, Elsa?’ I said again. ‘Was it like the rest of them? Did someone cut his throat?’

‘DC Wolfe,’ Whitestone said calmly, ‘get out of here.’

I ignored her.

‘Elsa? You have twenty years of experience. You’re in a million-pound state-of-the-art mortuary. You must know how he died.’

Whitestone gripped my shoulder hard enough to turn me around. How could such a slight woman summon up such reserves of physical strength? There was a rage in Whitestone, and she let me glimpse it now.

‘You think someone cut his carotid arteries, don’t you, Max?’ she said. ‘You think someone stuck a commando dagger in his neck and then torched the house. You think our killer is still out there.’

‘That’s exactly what I think.’

Whitestone gestured at the blackened corpse. ‘But why would they bother? I mean, really – look at the state of him. Why would anyone bother cutting the poor bastard’s throat?’

‘Because he wouldn’t commit murder with fire,’ I said. ‘Too unpredictable.’

‘Why is this murder? I saw TDC Wren’s report. I’ve spoken to Gane and Fire Officer Truman. A rich, chain-smoking drunk drops a cigarette butt near a fuel tank. The next thing you know – smoked Salman. Why exactly does that surprise you?’

‘Do you know what oxidation is, Max?’ Elsa said gently. ‘It’s what fire does. It’s what fire is. Oxidation is what happens when a fuel substance combines with oxygen to produce light and heat. It’s what makes fire a living, destructive entity.’ She looked at the burned piece of meat on the stainless steel slab. ‘There’s no evidence that someone cut his throat. Because fire destroys everything.’

At the Cromwell Green entrance to the Palace of Westminster, I showed them my warrant card.

I kept it in my hand as I went through the security turnstiles, Big Ben ringing in the sky high above, then past the armed officers in twos and fours cradling their Heckler & Koch assault rifles and finally through the search point just before you enter the great expanse of Westminster Hall.